blob: b3bd205dfbf6cc2cbb23bd542fbc5673d76660f8 [file] [log] [blame]
* Copyright 2023 Google LLC
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
* This file contains implementations of SkPixmap methods which require the CPU backend.
#include "include/core/SkAlphaType.h"
#include "include/core/SkBitmap.h"
#include "include/core/SkBlendMode.h"
#include "include/core/SkCanvas.h"
#include "include/core/SkImageInfo.h"
#include "include/core/SkMatrix.h"
#include "include/core/SkPaint.h"
#include "include/core/SkPixmap.h"
#include "include/core/SkRect.h"
#include "include/core/SkRefCnt.h"
#include "include/core/SkShader.h"
#include "include/core/SkSurface.h"
#include "include/core/SkTileMode.h"
#include "src/shaders/SkImageShader.h"
#include <utility>
struct SkSamplingOptions;
bool SkPixmap::scalePixels(const SkPixmap& actualDst, const SkSamplingOptions& sampling) const {
// We may need to tweak how we interpret these just a little below, so we make copies.
SkPixmap src = *this,
dst = actualDst;
// Can't do anthing with empty src or dst
if (src.width() <= 0 || src.height() <= 0 ||
dst.width() <= 0 || dst.height() <= 0) {
return false;
// no scaling involved?
if (src.width() == dst.width() && src.height() == dst.height()) {
return src.readPixels(dst);
// If src and dst are both unpremul, we'll fake the source out to appear as if premul,
// and mark the destination as opaque. This odd combination allows us to scale unpremul
// pixels without ever premultiplying them (perhaps losing information in the color channels).
// This is an idiosyncratic feature of scalePixels(), and is tested by scalepixels_unpremul GM.
bool clampAsIfUnpremul = false;
if (src.alphaType() == kUnpremul_SkAlphaType &&
dst.alphaType() == kUnpremul_SkAlphaType) {
src.reset(, src.addr(), src.rowBytes());
dst.reset(, dst.addr(), dst.rowBytes());
// We'll need to tell the image shader to clamp to [0,1] instead of the
// usual [0,a] when using a bicubic scaling (kHigh_SkFilterQuality).
clampAsIfUnpremul = true;
SkBitmap bitmap;
if (!bitmap.installPixels(src)) {
return false;
bitmap.setImmutable(); // Don't copy when we create an image.
SkMatrix scale = SkMatrix::RectToRect(SkRect::Make(src.bounds()), SkRect::Make(dst.bounds()));
sk_sp<SkShader> shader = SkImageShader::Make(bitmap.asImage(),
sk_sp<SkSurface> surface =
SkSurfaces::WrapPixels(, dst.writable_addr(), dst.rowBytes());
if (!shader || !surface) {
return false;
SkPaint paint;
return true;